Method of making insulating blocks



Aug. 8, 1933.

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METHOD OF MAKING INSULATING BLOCKS Filed Aug. 27, 1930 2 Sheets-Sheet 2Patented Aug. 8, 1933 PATENT OFFICE 1,921,524 7 METHOD or MAKINGmsom'rmo BLocKs William L. Hodges, Cambridge, Mass.,

to Bemis Industries,

assignor Incorporated, Boston,

Mass., a Corporation of Delaware Application August 27, 1930. Serial No.478,125

.2Clai This invention relates to an improved type of insulating block,and particularly to a substantially solid, relatively bulky,block-formed of felted fibrous material, such as felted wood orvegetable fibers and to a process of' making the same. The copendingapplication of Ralph S. Frobisher Serial No. 453,993, filed May 20,1930, discloses a method and apparatus for producing a comparativelythick integral block of porous or lightly felted fibrous materialwhich.is felted froma water pulp. For this purpose a plurality ofperforated cores are disposed within a foraminous casing, which in turnis located in a vacuum jacket, and pulp is introduced through the coresand collects about the same and between the sameand the jacket toprovide a block of relatively great thickness, having a plurality ofparallel core openings extending therethrough. The copending applicationof Ralph S. Frobisher, Serial No. 429,607, filed February 19, 1930, isdirected more particularly to a block of the character just described.

Blocks of the character disclosed in the aboveidentified copendingapplications are advantageous since they may be relatively thick and yetlight in weight. For example, under conditions of commercial productionit has been found impractical to manufacture fiber boards upon a feltingor making screen with a thickness substantially over one inch, while inaccordance with the above-identified applications a block may beprovided having a thickness of as much as eight inches at a cost muchlower than that which would be involved by the superimposition of a.plurality of separate fiber board lamina to provide a block ofcorresponding thickness or heat insulating ability.

' The present invention is more particularly directed to the provisionof a relatively thick block which may be formed of the units or blockssuch as are provided in the above-identified Frobisher applications,which however will be free from the core openings that characterize theblocks shown in these applications, and accordingly will afford materialhaving especially high ability, since even the limited, but inobjectionable, heat conduction resulting from convection currents in thecore openings may be avoided by the present invention. On the otherhand,this invention permits the provision of a block having a given thicknessor a given heat non-conductive capacity at a much lower cost than thatwhich would be involved were a plurality of ordinary fiber boardlamina-t0 be combined to attain a similar result.

In accordance with the present invention, a block of the characterdisclosed in the copending Frobisher application is split or cut intotwo similar slabs, the plane of cutting being substantially defined bythe parallel central axes of the core openings. Thus each of theoriginal blocks provides a pair of similar slabs which are characterizedby having a plurality of substantially semicircular grooves or recessesupon one face which are separated by rib portions having substantiallyplane faces in alignment with each other. The recessed faces of theslabs are then brought into mutual juxtaposition with the protuberantportions or ribs of one slab engaging the recesses of the other slab,and suitable pressure is employed to force the faces of the slabs intomutual engagement or close juxtaposition so that a substantially solidblock is provided. The lightly felted fibrous material is particularlyadvantageous in permitting this desirable result and in permitting thesemi-circular recesses and the plane surfaces therebetween to bedeformed and to conform to the face of the adjoining slab, so that atortuous joint is provided between the slabs which has substantially theform of a sinusoidal curve. The slabs as thus pressed into engagementmay be held together in any suitable manner. For example the recessedfaces of the slabs may be coated with a suitable agglutinant before theyare pressed into engagement.

I have found it particularly advantageous however to interpose a sheetof fibrous material, such as cardboard or paper between the recess facesof the slabs, securing the paper by suitable adhesive or agglutinant toboth'of the recessed faces. Not only does the paper aid the bonding ofthe slabs, but it also provides a wall separating minute irregularitieswhich normally occur upon the faces of the core openings, thus'tendingto minimize any local convection currents which might otherwise be setup, and occasionally preventing depressions upon adjoining slab facesfrom combining to form a crevice of appreciable size. In most cases,after the slabs are combined in this manner, their edges provide marginsor overlap- Fig. 2 is a perspective view of an end portion of a slabwhich is formed by cutting a block of the type shown in Fig. 1 along amedian plane;

.Fig. 3 is a perspective view of portions of a pair of slabs with theirprotuberant and recessed parts in mutual registration, showing themanner in which the slabs are originally brought into engagement;

Fig. 4 is a view of a block which may be formed by pressing the slabs ofFig. 3 into firm adhesive engagement, and trimming the ends of theslabs; and

Fig. 5 is a similar view showing such a block with a flexible fibroussheet interposed between the slabs.

Referring to the accompanying drawings, and first more particularly toFig. 1 thereof, which is a broken perspective view of a block such as isdisclosed in the copending applications referred to above, it may beseen that such a block is provided with opposite planar surfaces 2, anda plurality of intermediate core openings 3 which are disposed inparallelism to the planar surfaces 2 and substantially halfwaytherebetween; also the block may be provided with end grooves 4 whichpreferably are of semi-circular form, the grooves having the samegeneral dimensions as the intermediate core openings 3, and the planaredge surfaces 5 extending from these grooves to the main planar surfaces2. Similarly the ends of the block may be planar with the openings 3extending from one end to the other. A block of this characterordinarily is characterized by a somewhat closer aggregation of thefibers, designated by numeral 10, adjoining the outer faces of theblock, this denser structure resulting from the tendency of the fibersto move toward the outer foraminous lining of the making form under theaction of vacuum and liquid head. Inwardly of its outer faces the blockis characterized by a looser felting of the fibers, and is accordinglymore readily compressible, possessing however considerable resilience ortendency to regain its original shape after compression. Adjoining thecore openings, particularly if rotary cores are employed, there is atendency for the fibers to lie in directions preponderantly tangentialto the opening, thus providing an arch-like arrangement of thefibers inthis part i of the block.

A block of the character just described is more fully disclosed anddescribed in the copending application Serial No. 429,607 referred toabove, and is particularly referred to as the material from which theproducts of the present invention are made.

While 'under some conditions it may be desirable to sever aplanar layeror laminae from the outer portions of the original block to provide afiber board having the additional strength of the stirface layer or skinof the original block, and thus leave a block of the same general shapeas shown in Fig. l, but with outer faces which are relatively soft andyieldable, under most conditions I prefer to employ an original block asmanufactured with its relatively more dense and. stronger structureadjoining the outer faces, and particularly the planar faces 2.

The first step of the process of manufacturing a solid block of anoriginal block shown in Fig. 1, comprises the cutting of the originalblock 1 along a median plane, (indicated by dot and dash lines anddesignated by the symbol M in Fig. 1) which extends through the centralaxes of the core openings. The block may be cut in any suitable manner,as for example by a band saw. The

original block is thus divided into two slabs, on

'24 which defines the surface of a quarter of a cylinder correspondingto the semi-cylindrical surfaces of the recesses 23. Between each of therecesses 23 and between each recess or groove portion 24 and theadjoining recess 23, is a planar surface 25 formed by the cutting of theoriginal block into separate slabs.

A pair of substantially similar slabs 20, which are formed in thismanner, may then be brought into juxtaposition, as shown in Fig. 3, withtheir grooves and intervening ribs in mutually staggered andinterfitting relation, so that the recessed portions 23 of each slabreceive the planar face portions 25 of the other slab, while theremaining planar face portion 25 of each slab engages a quartercylindrical groove 24 at the end of the other slab. The slabs as thusbrought into contact are then pressed into firm engagement with eachother, for example with material having a specific gravity ofsubstantially 0.15 to 0.25, a pressure of between 10 to 75 pounds persquare inch, and preferably between 25 and 50 pounds per square inch maybe employed to distort the recessed faces of the slabs, so that they arein substantially continuous mutual contact through' out, as illustratedfor example in Fig. 4. Due to the yieldability and elasticity of thefelted fibrous material, the pressure which is thus imposed upon theslabs and which is effective in distorting their recessed faces, doesnot necessarily result in material permanent compression of the feltedfibrous structure, except adjoining the tortuous-joint between the slab.In other words, when the pressure is released the thickness of thematerial which has been somewhat decreased by the imposed pressure, willagain increase so that the material nearly regain its original degree ofporosity and heat insulating ability.

It is thus evident that felted fibrous material of this character isparticularly advantageous in permitting the firm, substantiallycontinuous, engagement of its recessed and ribbed faces in the mannerjust described, without necessitating any substantial permanentreduction in porosity or marked increase in weight per unit volume. Theslabs as pressed into engagement may be retained in this position toforman integral, substantially solid block by any suitable means. Forexample, as shown in Fig. 4, a layer of agglutinant 27 may be disposedbetween the faces of the block, the opposite recessed faces preferablybeing coated with the agglutinant before the pressure is applied to theslabs. Any suitable agglutinant, such as silicate of soda composition, acasein or animal glue, or the like may be employed for this purpose.Obviously the length of time during which pressure is applied to theblock depends upon the setting characteristics of the agglutinant andmay vary between a few minutes and several hours. Blocks when formed inthis manner originally will have oppositely projecting extensions orrabbeted end portions, which however ordinarily are trimmed ofito'provide continuous planar side surfaces 29, as shown in Figs. 4 and5. 7

As shown in Fig. 5, I have obtained somewhat more satisfactory resultsby imposing a sheet of flexible fibrous material, such as paper,designated brought into juxtaposition, as shown in Fig. 3.

tive softness and porous nature of its core.

The employement of the paper layer 30 is particularly advantageous notonly in affording a strong joint between the slabs, but also inseparating small irregularities'which ordinarily occur in the 7 coreopenings, so that such irregularities upon the opposite slabs do notcombine toprovide larger openings which might involve some heat loss dueto convection currents. The paper automatically adjusts itself to thedensity and exact shape of the adjoining surfaces of the slabs and formsa suitable anchoring medium to which the rela tively soft distortedmaterial is firmly secured, while in the case of substantiallyregistering recesses upon the adjoining faces of opposite slabs, thepaper layer separates these recesses and thus cuts down the possibleheat loss due to convection currents.

A block of the character disclosed herein is advantageous for manypurposes, as for example in buildings, refrigerators, refrigerator cars,or the like, where excellent heat insulating ability is a primedesideratum. Furthermore, such blocks may be readily handled since theyare light in weight, although comparatively bulky, so that theinstallation of heat insulating material of this character may bereadily accomplished. Furthermore, the outer skins or denser surfacelayers 10 provide the block with considerable form-retaining abilitydespite the rela- A block of this character may be-manufactured in athicknes's,for example of four to six inches, at a cost much lower thanwould be involved if separate fiber board laminae were to be secured insuperposed relation, while an unusually high heat insulating ability isprovided. For example,

the coeflicient of heat conduction of material of this character may besubstantially as high as that of granulated cork board.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

I claim: g

1. Method of making substantially solid insulating blocks out oforiginal blocks formed of yieldable material with a plurality of coreopen- .ings extending therethrough and having their central axes inacommon plane, which comprises cutting each original block substantiallyin the, plane of the axes to provide a pair of slabs each having similarrecesses separated by aligned plane surface portions, interfitting therecesses and aligned plane surface portions of a pair of slabs, andpressing the slabs together until their recessed faces are substantiallyin continuous contact and adhesively securing the slabs in theirinterfitting relationship.

'2. Method of making substantially solid insu-' lating blocks out oforiginal blocks formed of yieldable material, which have a plurality ofcore openings extending therethrough withtheir central axes in a commonplane, which comprises cutting each original block substantially in theplane of the axes to provide a pair of slabs with similarrecesses-separated by aligned plane surface portions, disposing aflexible sheet of material between the recessed faces of a pair of slabswhile interfitting the recesses and plane face portions of the slabs,and adhesively securing the recessed faces of the slabs to oppositefaces of the sheet while applying pressure to the slabs to cause theirsubstantially continuous surface contact with the sheet.

WILLIAM L. HODGES.

